Double-Side Cocatalytic Activation of Anodic TiO$_2$ Nanotube Membranes with Sputter-Coated Pt for Photocatalytic H$_2$ Generation from Water-Ethanol Mixtures

TL;DR

This study demonstrates that double-side sputter-coating of Pt on TiO$_2$ nanotube membranes enhances photocatalytic H$_2$ production from water-ethanol mixtures by optimizing electron transfer and light absorption, outperforming single-side decoration.

Contribution

It introduces a novel double-side Pt-decoration method on TiO$_2$ nanotube membranes, improving hydrogen generation efficiency through optimized cocatalyst distribution.

Findings

Double-side Pt-decoration increases H$_2$ production rates.

Distribution of Pt at both tube extremities is more effective than total Pt amount.

Membrane configuration influences light absorption and electron transfer.

Abstract

Self-standing TiO$_2$ nanotube layers in the form of membranes are fabricated by self-organizing anodization of Ti metal and a potential shock technique. The membranes were then decorated by sputtering different Pt amounts i) only at the top, ii) only at the bottom or iii) at both top and bottom of the tube layers. The Pt-decorated membranes are transferred either in tube top up or in tube top down configuration onto FTO slides and investigated after crystallization as photocatalysts for H$_2$ generation using either front or back-side light irradiation. Double-side Pt-decoration of the tube membranes leads to higher H$_2$ generation rates (independent of tube and light irradiation configuration) compared to membranes decorated at only one side with similar overall Pt amounts. The results suggest that this effect is not ascribed to the overall amount of Pt cocatalyst as such but rather to its distribution at both tube extremities. This leads to optimized light absorption and electron diffusion/transfer dynamics: the central part of the membranes act as light harvesting zone and electrons therein generated can diffuse towards the Pt/TiO$_2$ active zones (tube extremities) where they can react with the environment and generate H$_2$ gas.